[Milsurplus] Pre-WWII Aircraft Radio

[Ray Fantini]

Assumed all GO were the same, did not know Westinghouse and GE were different sets. possible GE had forward looking and working design but considering the state of the art before 1938/39 anything that was capable of working continually over that range, producing usable power and stable would be exceptional if not unique. Perhaps the GE set used the PA section as a doubler to extend range a trick used by many armatures for a time when there were no worries about suppressing unwanted harmonics? The 1936 "Radio Armatures Handbook" not the ARRL one but another of the same name has a diagram and plans for a medium power CW and phone transmitter biased on the 803 that's almost identical to the TBW/GO-9, older oscillator and driver tube but still pentodes and suppressor modulation of the PA. it's not a band switching design being that it used plug in coils that covers 80, 40, and 20 meters. Perhaps the GO/TBW line was biased on armature design?
Ray F.

-----Original Message-----
From: milsurplus-bounces at mailman.qth.net [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Mike Morrow
Sent: Friday, June 10, 2011 12:44 PM
To: milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] Pre-WWII Aircraft Radio

Ray wrote:

> Both TBW and GO series transmitters use an 837 as a master oscillator
> and a second stage 837 intermediate amplifier driving an 803 PA tube.

The GO-9 and the TBW are Westinghouse designs that apparently differ
considerably from the GE GO-4, -5, and -6.

Have anyone really have any technical information about the GE designs.
The Westinghouse design is not an issue in this discussion.  These
people weren't idiots, and there were three GE GO sets with the 27000
kHz upper limit.

> ...also all GO series transmitters were CW only. Who would pair a
> command type receiver with a CW only transmitter?

The RU-* series served both command and liaison service from 1932 to
end of WWII with the GF, GO, and GP series (and a few rare oddballs).
Is that the one you mean?  If by "command type receiver" you are
referring to the RAT/RAT-1, then I list these observations:

(1)  The RAT/RAT-1 are not command set receivers.  There had in 1938
     never been a RAT/RAT-1 type of receiver in command service
     outside the developmental Type K of 1937 and 1938.
(2)  When the GO-4 appeared in 1938 with its 27000 kHz capability,
     there were no aircraft receivers anywhere capable of matching that.
     Certainly the RU capability could not easily be extended beyond its
     13575 kHz limit.  When A.R.C. burped out the RAT/RAT-1 in 1939, to
     go with the RU-11/12 that it also produced, the RAT/RAT-1 would
     have been the finest aircraft set available for those frequencies
     in the world.
(3)  The stability issues of the superheterodyne RAT/RAT-1 used with
     with a GO-4/5/6 transmitter were likely as good as any aircraft
     receiver set in existence at that time.
(4)  The GO-* was not CW (A1) only.  It was also MCW (A2), produced from
     the 800 Hz AC supply applied to the PA plates.  That would reduce
     the stability requirement for any receiver copying the GO-*.  However,
     it is unlikely that liaison sets were often used for aircraft-to-aircraft
     communications, so the issue of stability revolves more around the
     characteristics of the shore/ship installation.
 
> Perhaps the early high frequency ideas were what engineering thought the
> radio was capable of but in reality when everyone found out how poorly
> the radio worked at those frequencies they revised the specs.

An interesting speculation.  There likely were some problems that were
not in 1940 worth sorting out with war clouds overhead.  Thus, by 1945 
there were some aircraft HF sets operated to 18100 kHz, but most stopped
at 9050 kHz.  However, I would not cast aspersions on the performance
of the GO-4/5/6 and RU-12/RAT-1 without some credible evidence that the
system was NOT servicable.  Most likely, it just wasn't worth the effort
since few shipboard transmitters of that era worked above 18100 kHz either. 

> The CQ Surplus conversion manual shows how to use your TBW or GO on
> ten and fifteen meters. Their instructions are to gut all the tuned
> circuits...

That observation is complicated by the fact that the Westinghouse TBW and
GO-9 design was NEVER designed to get near those frequencies.  The GE
GO-4/5/6 was.  It is doubtful any ham ever had access to a GE GO-* as
surplus.  In any event, we know how dead-on technically accurate those
post-WWII ham RF-engineer-wannabes were with their evaluations of surplus
military gear. :-)

Mike / KK5F